Torsional vibration dampers generally consist of a ring-type support member and a ring-type flywheel member coupled to each other with a ring-type spring member which enables the two members to be rotated with respect to each other in a springy manner for a certain limited range. Such a torsional vibration damping system has the disadvantage of being able to damp effectively, or to absorb completely, the torsional vibrations acting either on the ring-type support member or ring-type hub member only within a very narrow resonant frequency range. Therefore, numerous experiments have been made to construct torsional vibration dampers having a larger working range.
Concerning these efforts, centrifugal-type torsional vibration dampers have been developed, wherein additional centrifugal mass switching members are provided in between an inner hub ring and an outer ring-type centrifugal mass member which are coupled by segmented ring-type rubber spring means. The centrifugal mass switching members are pressed onto the radially inner surface of the outer ring-type centrifugal mass member by the centrifugal force acting when the damper is rotating, thereby effecting a frictional connection, by which fact additional spring members are coupled to the ring-type centrifugal mass member and by which additional spring members the centrifugal mass members are coupled rotationally elastically to the hub ring. Thus, the torsional vibration damper can be provided with a second resonant frequency by means of the switch-type coupling of an additional spring system, which coupling is dependent upon the centrifugal force.
Apart from abrasion problems, which are caused by the frictional connection switching behaviour, such a torsional vibration damper can be provided only with a second or possibly a third, resonant frequency. However, a continuous change of the spring characteristic curve of the torsional vibration damper dependent upon the number of revolutions principally cannot be reached by such a torsional vibration damper according to this prior art.
Finally, a torsional vibration damper with characteristics dependent upon the centrifugal force is known from the prior art wherein the torsional vibration characteristic curve thereof is a continuous function of the number of revolutions. This torsional vibration damper is constructed as a sleeve-type rubber metal spring such that the outer ring-type sleeve serving as a support member is at least principally rigidly connected with the shaft to be damped, wherein an inner sleeve-type ring, which is divided in at least two parts, is shaped as a ring-type centrifugal mass member. The ring-type support member and the ring-type centrifugal mass member are connected elastically or, seen as a vibration system, are coupled to each other by a rubber spring, wherein these two members can be rotated with respect to each other for a certain limited range. The rubber spring, which possibly may be segmented, is shaped as a segment of the wall of a cylindrical tube connecting the radially outer surface of the respective centrifugal mass segment with the radially inner surface of the ring-type support member, wherein the contact surfaces are complementarily shaped.